Disable Cache or Clear Cache

Im using WPThumb to build images for a slideshow echo '<li><img src="'.wpthumb( $propertyimg, 'width=600&height=400&crop=1&cache=false' ).'" border="0"/></li>'; These images are likely to update but their filenames stay the same. Im trying to set cache to false so that a cache/local version is not created. But it always seems to create a local version. 1> Is it possible to prevent caching? 2> Is it possible to clear the cache entirely so that all images are rebuilt? https://wordpress.org/plugins/wp-thumb/